used to do 过去常常（表示现在不再） used to do过去常常，过去曾经；过去常常做某事 He used to do his homework on Sunday, but now he often does homework on Saturday. 他过去在星期天做家庭作业，但是现在他经常在星期六做作业。 eg: I used to swim in the lake near my village when I was young. be used to doing习惯于做某事 eg: My grandpa is used to going for a walk after dinner. be used to do 被用于。。。 eg: Wood can be used to make paper ＂I used to do this rather regularly, particularly with shoplifters, ＂ the judge said. “我以前经常这么判决，特别是对那些商店扒手，”法官说。 有一点需要补充。在选择题中看到be used to时，应当首先根据句子判断其所要的意思是什么，然后在决定选哪一个.另外，当习惯做某事时，由于to是介词，所以要加动名词doing；而be used to do sth.是使用的被动语态，所以后面加动词原型.另外，如果强调渐渐适应，还可以用get used to doing sth.